The homogeneity of two-dimensional shapes across sight and touch

When Locke says that a simple idea of shape is received by both sight and touch, he means that a simple idea of a two-dimensional shape is received through both senses. A simple idea of a triangle, for example, is received by both sight and touch. That is, a triangular shape delivered by sight, for example, is the same as a triangular shape delivered by touch. Mackie is right in claiming that Locke would give a positive answer to a two-dimensional version of Molyneux’s Question. It is a version of Molyneux’s Question with a square and a circle, which was introduced by Diderot.42It follows from Locke’s view that a newly sighted man, shown a square and a circle, would be able to have visual experience as of a square and a circle. Moreover, a square and a circle delivered by sight are the same as a square and a circle delivered by touch. Molyneux’s subject would receive simple ideas with which he is already familiar because of tactile perception. Then the subject would correctly say that the shapes put before him are a square and a circle.43 Evans objects to

Locke writes as follows in the first section of the chapter on complex ideas: ‘… as the mind is wholly passive in the reception of all its simple ideas, so it exerts several acts of its own, whereby out of its simple ideas, as the materials and foundations of the rest, the other are framed’ (Locke (1997), II, xii, 1, p. 159).

42

Mackie (1976), pp. 30-1; Diderot (1977), p. 55.

43

In the original case of Molyneux’s Question, the newly sighed subject would have visual perception as of a polygonal shape and a circle. It follows from Locke’s view that the two shapes delivered by sight are the same as a polygonal shape and a circle

Mackie by insisting that Locke allows no visual perception of shape at all.44On Evans’ interpretation of Locke, a newly sighted man would not even have visual perception as of a square and a circle. Evans thus denies that Locke would have given a positive answer to Diderot’s two-dimensional version of Molyneux’s Question. Having rejected Evans’ and Bolton’s interpretation, we can support Mackie’s claim.

Notice that a positive answer to Diderot’s version of the question would not contradict Locke’s motivation for discussing the question. Locke discusses Molyneux’s Question in order to illustrate that an unnoticed judgement alters ideas received by sight, but not to argue that visual shape experience and tactile shape experience are heterogeneous from the first-person viewpoint. (As we will see, it is Berkeley’s motivation to argue for the latter thesis.) If Locke’s motivation was to propose the latter thesis, it might be coherent for him to give a negative answer even to Diderot’s version of the question. But since his purpose is to illustrate the former view, it would cause him no problem to allow that plane shapes delivered by sight (on the basis of which judgements could be made) are the same as those delivered by touch. From the above considerations, we can conclude that the following phenomenological thesis is held by Locke:

(Lvt) There is no difference between two-dimensional shapes delivered by

sight and two-dimensional shapes delivered by touch.

delivered by touch. So, if Locke is right, Molyneux’s subject might incorrectly say that the shapes placed before him are a polygonal shape (say, a hexagon) and a circle.

44

Mackie and Michael Ayers respond to a possible objection to Locke’s negative answer.45I would like to discuss this objection, because a correct response to it given by Mackie and Ayers would support my attribution of (Lvt) to Locke. Whereas

Locke defines an ‘idea’ as ‘whatsoever the mind perceives in itself, or is the immediate object of perception, thought, or understanding’, he defines a ‘quality’ as ‘the power to produce any idea in our mind’.46‘Qualities’ in the external world are the causes of ‘ideas’ in the mind. Locke, then, classifies qualities into ‘primary’ and ‘secondary’ qualities. ‘Primary qualities’, on the one hand, are such qualities as ‘solidity, extension, figure, motion, or rest, and number’, which external objects must have.47 Examples of ‘secondary qualities’, on the other hand, are ‘colours, sounds, tastes, etc.’, which are dependent on primary qualities.48 For example, according to Locke, the secondary quality of colour is a power of insensible primary qualities, i.e. a power of insensible particles which, having certain primary qualities, hit our eyes to produce an idea of colour.49Now, one essential difference between ‘primary’ and ‘secondary’ qualities is in that ideas of primary qualities resemblethe

external objects, whereas ideas of secondary qualities do not.50He asserts that ‘the

ideas of primary qualitiesof bodies, are resemblancesof them, and their patterns do

really exist in the bodies themselves’.51Locke, including shape as a primary quality, thinks that an idea of shape the mind receives resembles the shape of the object causing the idea. One might then insist that Locke should give a positive answer to Molyneux’s Question. Locke would acknowledge that the ideas of a cube and a

45

Mackie (1976), pp. 28-32; Ayers (1991), Vol. I, pp. 65-6.

46

Locke (1997), II, viii, 8, p. 134.

47

Ibid., II, viii, 9, p. 135.

48

Ibid., II, viii, 10, p. 135.

49

Ibid., II, viii, 13, p. 136; II, viii, 23, p. 139.

50

Ibid., II, viii, 15, pp. 136-7.

51

globe Molyneux’s subject has received by touch resemble cubical and global objects in the external world, respectively. Locke, one might claim, should also acknowledge that the ideas of a cube and a globe Molyneux’s subject receives by sight when he begins to see, too, resemble the cube and the globe in the environment, respectively. The outcome would be that the ideas Molyneux’s subject receives by sight resemble ideas of a cube and a globe he has received by touch, because both pairs of ideas resemble the same qualities, i.e. a cube and globe, in the external world. The idea is that two things resembling the same thing should resemble each other. Thus, it might be claimed, Locke should give a positive answer to Molyneux’s Question.

Indeed, one of Bolton’s motivations for her interpretation is to respond to the above objection. According to her, Locke would deny that there is any visual shape perception at all. If so, it would plainly follow that no ideas Molyneux’s subject receives by sight would resemble any idea of shape he has received by touch. Locke would then be able to justify his negative answer despite his view of the resemblance between primary qualities and ideas of them. We have rejected Bolton’s interpretation, so we can say that this response is incorrect. The response suggested by Mackie and Ayers should be adopted. The response is made by interpreting Locke in the way we have. Locke answers Molyneux’s Question negatively because he thinks that Molyneux’s subject would have visual experience as of two plane shapes. Suppose that his visual experience is as of a hexagon and a circle. He would receive ideas of a hexagon and a circle, which resemble a hexagon and a circle (rather than a cube and a globe) existing in the external world. Thus, the ideas Molyneux’s subject receives by sight would not resemble the same external shapes as do the ideas of a cube and a globe he would have received by touch. Rather, the ideas he receives by

sight would resemble the same external shapes as do the ideas of a hexagon and a circle he would have received by touch.

The above criticism of the possible objection to Locke would reinforce my interpretation of drawing (Lvt) from Locke’s account. We receive ideas of plane

shapes by sight. They resemble the plane shapes in the environment. Ideas of plane shapes received by touch, too, resemble the plane shapes in the environment. Thus, if the resemblance here is transitive, ideas of plane shapes received by sight would resemble ideas of plane shapes received by touch. That is, plane shapes delivered by visual perception would resemble plane shapes delivered by tactile perception.